Responses

He knew it was clyde from that scene where clyde kiss yu in front of them. Also, he knew that clyde was the one who bit Yu's neck(chapter 5) and knew that clyde was the one that yu is mentioning when he said that the bite from his nape was because of a dog. Which leads to yu's colleague's cconclusion that clyde is the dog.
"it's the dog"
SIR???? WERE U JOKING OR DO U JUST HAVE A MASSIVE ACCURATE GAYDAR